The London group's second album has sold 540,000 in its first week, according to Nielsen SoundScan - the year's third-highest debut behind Taylor Swift's Red, which sold 1.2 million units in its first week earlier this month and Mumford And Sons' Babel, which sold more than 600,000 albums in September in its debut week.

"We just want to say a massive thanks to all the fans who have supported us," band member Harry Styles, 18, said.

The album also debuted at number one in the UK this week. The fivesome's debut, Up All Night, came in at number two in last year; it was just released in March in America, where it hit number one and has achieved platinum status.

"We were a little bit nervous about how people were going to take it," 19-year-old Niall Horan said of the new album during tour rehearsals. "Everyone gets that second album syndrome."

But they say although they are excited, they will not be celebrating too much..."We're finishing rehearsing soon and we're going home to bed."

One Direction came third on the UK version of The X Factor in 2010, and have found international success this year.

They published a book and have a Nickelodeon show and 3D movie planned. They also made the cut for Barbara Walters' most fascinating people of 2012 list.

The group - which includes Harry, Niall, Zayn Malik, Liam Payne and Louis Tomlinson - will launch a worldwide tour in February.